Polyorganosiloxane composition has conventionally exhibited excellent weather resistance and durability when cured, and has therefore been used in adhesives or sealing materials. In recent years, there is a tendency that higher strength is required of the cured products of polyorganosiloxane compositions. As a polyorganosiloxane composition to cope with this demand, for example, there is known a composition in which a filler material formed of an inorganic or organic compound is incorporated (see Patent Document 1).
Furthermore, the variety of materials on which adhesion is provided also tends to broaden, and as a polyorganosiloxane composition that is capable of satisfactory adhesion even to polybutylene terephthalate, high impact polystyrene, acrylic resin and the like, to which adhesion has been difficult, there is known a composition formed from a polyorganosiloxane, a silane compound having two or more hydrolyzable groups bonded to a silicon atom, and an additional reaction product of a vinyl group-containing bisphenol A and a silicone compound having an organo-oxy group (see Patent Document 2).